Hello Debra and Lorredan,
thank you for bringing the attention to this wonderful painting!
I think
Petrarch makes the identification of the subject clear:
"Pray, of your courtesy, what folk are these?"
"Ere long," he answered, "thou thyself shalt know,
Thyself being one of them: thou knowest not
How firm a bond is being made for thee.
Thy looks shall fade, and white shall be thy hair,
Before the bond I speak of is unloosed,
However much thy neck and feet rebel.
And yet, to satisfy thy youthful wish,
I'll answer, telling of our master first,
Who rives us thus of life and liberty.
For this is he whom the world calleth Love:
Bitter, thou see'st, as thou wilt see more clearly
When he shall be thy lord, as he is ours
Gentle in youth and fierce as he grows old,
As who makes trial knows, and thou shalt know
In less than a thousand years, I prophesy.
Idleness gave him birth, and wantonness,
And he was nursed by sweet and gentle thoughts,
And a vain folk made him their lord and god.
Some of his captives die forthwith; and some
More pitilessly ruled, live out their lives
Under a thousand chains and a thousand keys.
..."
This sentence from the NGA site does not make sense:
“The panel is unlikely to represent the Triumph of love however, as in all depictions of the subject the only person with bound hands is Cupid.”
In the triumph of Love, Love is the winner and the lovers are his captives. Why should triumphant Love be represented with bound hands?
See also
this image published by Michael J. Hust on wikimedia.
BTW, Roberto Longhi, who identified the subject of this fragment, was one of the most important Italian art historians. In particular, he
rediscovered Caravaggio who had been forgotten for three centuries.